1. Field of the Invention
This invention relates to a micro-processing method of forming a structure adapted to confine electrons within a micro-region and, more particularly, it relates to a micro-processing method to be used for processing applications of the above described type that use a scanning probe microscope.
2. Related Background Art
The recent development of scanning tunneling microscopes (hereinafter referred to as STM) [G. Binnig et al., Phys. Rev. Lett., 49, 57 (1982)] allows a direct observation of a real spatial image of a specimen on an atomic or molecular level.
A scanning tunneling microscope is designed to scan an electroconductive specimen by means of a probe electrode, controlling the distance between the probe electrode and the electroconductive specimen to maintain the tunneling current flowing therebetween so that the electron cloud of the surface of the specimen and the profile of the specimen may be observed on the order of sub-nanometers on the basis of the data on the control signal used for controlling the distance.
Meanwhile, the atomic force microscope (hereinafter referred to as the AFM) has been developed as means for observing the surface of a specimen also on the order of sub-nanometers.
With an AFM, the surface profile of a specimen can be observed on the order of sub-nanometers even if the specimen is not electroconductive. The technique of obtaining physical information of the surface of a specimen on the basis of the interaction between a probe and the surface of a specimen by two-dimensionally scanning the surface by means of the probe of an STM or an AFM is generally referred to as scanning probe microscopy (SPM), which has been attracting attention as means of observing the surface of a specimen with an enhanced level of resolution.
Now, formation of micro-structures on the order of the size of an atom is fully possible by utilizing the principle of SPM.
For instance, Japanese Patent Application Laid-Open Nos. 63-161552 and 63-161553 disclose a technology for applying a voltage to an insulation film utilizing the principle of STM and produce a change in the electroconductivity of the insulation film. With the disclosed technology, it is possible to produce in an object of micro-processing an area showing an enhanced level of electroconductivity which is as small as several nanometers.
Generally, a component element of an electronic device showing quantum effects can be formed by confining electrons within a very small region of a sub-micron size.
For instance, a structure referred to as quantum dot and showing an electron-confining effect can be obtained by forming a spherical or cubic electroconductive region of a size between several nanometers to several hundred nanometers and enclosing it within a non-electroconductive region.
Similarly, a structure referred to as quantum wire and showing an electron-confining effect can be obtained by forming a rod-shaped electroconductive region of a size between several nanometers to several hundred nanometers in diameter and enclosing it within a non-electroconductive region.
Thus, a structure of confining electrons within a very small region takes a vital role in realizing a device showing quantum effects.
However, it is difficult with a technology disclosed in either of Japanese Patent Application Laid-Open Nos. 63-161552 and 63-161553 to confine electrons within a very small region because an area with an enhanced level of electroconductivity realized by means of such a technology is electrically connected to a substrate electrode.